GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 23 May 2019, 03:58

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# The average marks obtained in a test by x students of a class was m.

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 55262
The average marks obtained in a test by x students of a class was m.  [#permalink]

### Show Tags

03 Jul 2017, 05:00
00:00

Difficulty:

85% (hard)

Question Stats:

35% (02:23) correct 65% (02:44) wrong based on 37 sessions

### HideShow timer Statistics

The average marks obtained in a test by x students of a class was m. Was (x + 3) the average marks obtained by three students with the lowest marks in the same test?

(1) If the lowest three marks were excluded, the average score of the class would have increased by three.
(2) m = 2x.

_________________
Manager
Joined: 02 May 2016
Posts: 77
Location: India
Concentration: Entrepreneurship
GRE 1: Q163 V154
WE: Information Technology (Computer Software)
Re: The average marks obtained in a test by x students of a class was m.  [#permalink]

### Show Tags

09 Jul 2017, 07:02
1
Bunuel wrote:
The average marks obtained in a test by x students of a class was m. Was (x + 3) the average marks obtained by three students with the lowest marks in the same test?

(1) If the lowest three marks were excluded, the average score of the class would have increased by three.
(2) m = 2x.

C ?

My understanding:

B doesnt help.

Using A:
say Sum of All/No Of Students=A/x=m
So A=mx.
Say Sum of lowest 3=L.
\frac{A-L}{x-3}=m+3
A-L=(x-3)(m+3)
A-L=mx+3x-3m-9
Use A=mx and change sides
L=3m-3x+9
L is sum of lowest 3, its average will be L/3=(3m-3x+9)/3= m-x+3
m could be anything, so Not sufficient.

Using m=2x from B,
L/3=2x-x+3=x+3

BUT I believe if C is the answer then there might be some kind of trap making A/B/E the answer.
Couldn't find the trap.
Waiting for OA and OE by expert!
Intern
Joined: 11 Apr 2017
Posts: 5
GMAT 1: 740 Q51 V39
GPA: 4
Re: The average marks obtained in a test by x students of a class was m.  [#permalink]

### Show Tags

09 Jul 2017, 07:29
1
C??

From 1 we can get that average marks obtained by three students with the lowest marks in the same test = (m-x)+3.

We have no Information about the relation between m&x and it may or may not be the case that m-x = x

2 doesn't help individually.

Combining 1 & 2 we get Average marks obtained by three students with the lowest marks in the same test = (m-x)+3 = (2x-x)+3 = x+3.

Hence C should be the answer.
Senior Manager
Joined: 06 Jul 2016
Posts: 363
Location: Singapore
Concentration: Strategy, Finance
Re: The average marks obtained in a test by x students of a class was m.  [#permalink]

### Show Tags

18 Jul 2017, 09:14
1
Bunuel wrote:
The average marks obtained in a test by x students of a class was m. Was (x + 3) the average marks obtained by three students with the lowest marks in the same test?

(1) If the lowest three marks were excluded, the average score of the class would have increased by three.
(2) m = 2x.

Average = $$\frac{Sum}{Number}$$ = $$\frac{S}{x}$$ = m
$$\frac{L}{3}$$ = x+3?

1) Lowest 3 marks = L
$$\frac{(S-L)}{(x-3)}$$ = x+3
=> S-L = mx+3x-3m-9
=> mx - L = mx+3x-3m-9
=> L = 3m-3x+9
$$\frac{L}{3}$$ = m-x+3
m = ?
Insufficient.

2) m = 2x
Doesn't help. Insufficient.

1+2)
$$\frac{L}{3}$$ = 2x-x+3 = x+3
_________________
Put in the work, and that dream score is yours!
Re: The average marks obtained in a test by x students of a class was m.   [#permalink] 18 Jul 2017, 09:14
Display posts from previous: Sort by